Day: September 20, 2013

Pure heart muscle cells that are ready for transplantation. This is one of the Holy Grails of regenerative medicine. Of course when working with pluripotent stem cell lines, isolating nothing but beating heart muscle cells is rather difficult. A new technique makes the isolation of pure cultures of beating heart muscle cells that much easier.

Researchers at Emory and Georgia Tech have developed a method that utilizes molecules called “molecular beacons” to isolate heart muscle cells from pluripotent stem cells. Molecular beacons fluoresce when they come into contact with cells that express certain genes. In this case, the beacons target cells that express heart-specific myosin.

Physicians can use these purified cardiac muscle cells to heal damaged areas of the heart in patient that have suffered a heart attack or are suffering heart failure. This molecular beacon technique might also have applications in other fields of regenerative medicine as well.

“Often, we want to generate a particular cell population from stem cells for introduction into patients,” said Young-sup Yoon, professor of medicine and director for stem cell biology at Emory University School of Medicine. “But the desired cells often lack a readily accessible surface marker, or that marker is not specific enough, as is the case for cardiac muscle cells. This technique could allow us to purify almost any type of cell.”

Gang Bao pioneered he use of molecular beacons and was a co-author of this publication. Yoon and is colleagues and collaborators grew mouse and human embryonic stem cells and induced pluripotent stem cells and differentiated them into heart muscle cells (cardiomyocytes). They then used molecular beacons to label only those cells that expressed messenger RNAs with just the right sequences. These molecular beacons hybridized with the mRNAs and fluoresced. Bao and others then used flow cytometry to sort the fluorescent cells from the non- fluorescent cells. The fluorescent cells have differentiated into heart muscle cells and were isolated from all the other cells.

These purified heart muscle cells could engraft into the heart of a mouse that had suffered a heart attack and they improved heart function and formed no tumors. This proof-of-principle experiment shows that this technique is feasible.

“In previous experiments with injected bare cells, investigators at Emory and elsewhere found that a large proportion of the cells are washed away. We need to engineer the cells into compatible biomaterials to enhance engraftment and retention,” said Yoon,